Typically, sleeping bags are used when a conventional bed and bedding are unavailable. For example, sleeping bags are used by backpackers, hikers, campers, mountaineers, and other users as portable beds or coverings. Sleeping bags are often durable sleeping coverings that provide a soft surface, insulation and weather resistance.
Consumers face a difficult task in finding a sleeping bag that is thermally efficient, comfortable, and lightweight. One type of sleeping bag, referred to as a “mummy bag”, tends to be shaped with a lateral taper to approximate the contour of the body of a user and thereby minimize the internal volume of the bag. Mummy bags attempt to conserve heat by minimizing air movement within, and from the bag. As a result, mummy bags are often suited for use in outdoor, colder ambient temperatures.
To enter typical mummy bags, a user must unzip the bag, and then get inside the bag. Due to the tight fit, the user may find it difficult to fully zip the bag, and furthermore, the zipped bag may be uncomfortable. For example, one drawback to the mummy bag is that some users feel discomfort due to the tight fit of the bag, which may reduce the user's range of motion. Another drawback of mummy bags is that the user is prevented from having external access without unzipping the bag and thereby compromising the warmth of the bag.
Some mummy bags include diametrically opposed zippered ports located along a side panel of the sleeping bag, between an overlying portion and an underlying portion. Although these bags include ports to allow the user external access, one drawback is that the constraint of the mummy bag makes it difficult for the user to access the zippers to open the ports. Moreover, these ports are located along the side panels at a position adjacent to the upper arms and shoulders of the user and the zippers are orientated generally parallel with the longitudinal length of the bag, making unzipping the ports difficult for users located within a closed bag. As a result, the user may be required to unzip the bag, introducing air flow into the bag and losing heat, to obtain enough access to unzip the ports and to extend the user's arm through the port.
Accordingly, a need exists for a sleeping bag that is comfortable, thermally efficient, and provides the user with external access from within the closed bag while preventing the introduction of air flow and loss of heat.